This invention generally relates to an instrument which uses a slotted memory metal tube to perform or assist in various medical procedures.
Surgical and other medical procedures are often performed at sites within a patient""s body. In the past, the only way to perform such medical procedures was to cut a large enough incision in the patient""s body to expose the operating site sufficiently to permit direct access by a physician. Such operations, however, typically caused a great deal of trauma to the affected tissue requiring lengthy periods for recovery and causing the patient substantial pain and suffering. With technological advances in the medical profession, more and more of these procedures are being performed using less invasive endoscopic and similar procedures. In general, endoscopic procedures include using an instrument having a delivery tube with an inner bore through which a tool can be inserted. With such an instrument, the delivery tube is usually inserted into the patient""s body by way of either a comparatively small incision or a body orifice and through a body cavity or hollow organ to the site desired. In this way, any trauma to the patient""s body can be generally limited to surrounding tissue along the insertion path of the delivery tube.
Many procedures have been limited to traditional direct access methods due to the size and method of operation of the tools used to perform the procedures. As a result, there is a need for tools which are more adaptable to use with endoscopic and similar procedures.
One object of the invention is a medical instrument with slotted memory metal tube.
Another object of the invention is a retrieval basket for small particles.
A further object of the invention is a tool for dilating vessels and other tubular structures.
Yet another object of the invention is a device for reaming vascular, other tubular structures, or different shaped cavities.
Still a further object of the invention is a pump for injection of a defined quantity of fluid.
Yet a further object of the invention is an optical system with an expanding section which allows inspection of the expanded area.
Another object of the invention is an internal gripper for holding soft tissue such as skin, nerves; arteries, or the like or for holding clips.
Yet a further object of the invention is an external gripper for attaching to stents, tissue, or skin.
Still a further object of the invention is a tool for expanding cavities for inspection.
A further object of the invention is an expandable plug for closing a cavity or tubular structure.
Yet another object of the invention is device for measuring the diameter of tubular structures.
Another object of the invention is a steerable catheter tip.
Still another object of the invention is a reinforced stent.
Additional objects, advantages, and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following description.
According to the present invention, the foregoing and other objects are attained by a medical instrument with slotted memory metal tube. A series of medical instruments can be made with the use of a shape memory tube with a transformation temperature that is above or below the ambient temperature. In the first case, the material behaves with the shape memory effect, and in the second case, the behavior is superelastic.
In all of the disclosed types of instruments, the wall of the tube has been provided with a plurality of slots in specific places, often near or at the distal end of the instrument, and in specific arrangements, which allow local variations in diameter, shape, and/or length. These variations can either be caused by the memory effect during temperature change or by superelastic behavior during change of the mechanical influences on the memory metal by the surrounding material. One possibility to activate the superelastic shape change can be the use of a second tube, surrounding the memory metal tube, sliding more or less over the area where the slots in the memory metal tube are placed. The second tube is used to control the final shape and it prevents shape changes at undesired moments, such as during the procedure of insertion into the human body. The delivery tube can be pulled backward over the central memory metal tube. As soon as the memory metal tube comes free, it can regain its preprogrammed shape whether by superelasticity or by temperature change.
Dependent on the intended function of the device, the amount and pattern of slots in the wall of the memory metal tube can be chosen. The slots can be made by a variety of methods, such as, but not limited to, etching, spark erosion, water jet cutting, abrasive water jet cutting, laser cutting, or any mechanical means. An expansion of the slotted part the desired programmed shape can be achieved by some internal or external mechanical means and, when the final heat treatment has been applied, the prestrained shape will be the new programmed shape. After removing the internal or external shaping tool, the memory metal tube is ready for use.
It is possible to make memory metal tubes which are deformed to a small diameter and which will return to a larger diameter in the slotted section by superelasticity or by shape memory effect. The reverse is also possible when the slotted section is opened to a larger diameter than the programmed diameter by some internal restraining means. It will return to a smaller diameter when it is released. The slotted section can be made in several places along the length of the memory metal tube and the programmed shapes can vary over the length of the tube.